The present invention relates generally to fuel systems for vehicles and, more particularly, to an electronic returnless fuel system for a vehicle.
It is known to provide a mechanical returnless fuel system for a vehicle, which includes a fuel delivery module, a fuel filter, a fuel pressure regulator, a fuel rail, and fuel injectors. In the mechanical returnless fuel system, a fuel pump of the fuel delivery module typically runs at the maximum flow at all times to deliver fuel to an engine of the vehicle. The purpose of the fuel pressure regulator is to maintain the fuel pressure as the fuel consumption at the engine varies. The fuel pump supplies an amount of fuel greater than the engine can consume. When the engine of the vehicle is turned off, the heat from the engine continues to heat the fuel rail and causes the pressure in the fuel rail to rise. The increased pressure causes the fuel pressure regulator to open and relieve the pressure by dumping the heated fuel into the fuel tank, which generates vapor in the fuel tank.
It is also known to provide an electronic returnless fuel system for a vehicle, which eliminates the pressure regulator and the attendant fuel tank vapor formation by providing a pressure relief valve to relieve the pressure and by controlling the speed of the fuel pump. An example of such an electronic returnless fuel system is disclosed in U.S. Pat. No. 5,237,975 to Betki et al. In this patent, a returnless fuel delivery control system regulates fuel rail pressure at the level needed for precise control of fuel mass flow to fuel injectors at both normal and elevated engine temperatures. Other examples of returnless fuel systems are disclosed in U.S. Pat. Nos. 5,379,741, 5,448,977, and 5,848,583.
In some fuel systems, the fuel tank may be of a saddle or dual tank type. In these types of fuel tanks, jet pumps are used as a low cost method to transfer fuel from a secondary side to a primary side of the fuel tank. However, the jet pump creates a lot of vapor when it transfers the fuel to the primary side of the fuel tank.
Therefore, it is desirable to provide an electronic returnless fuel system for a vehicle that lowers fuel tank pressures and reduces vapor generation and heat input into the fuel tank. It is also desirable to provide an electronic returnless fuel system for a vehicle that reduces excess fuel being dumped into the fuel tank.
It is, therefore, one object of the present invention to provide an electronic returnless fuel system for a vehicle that lowers pressures in a fuel tank for the vehicle.
It is another object of the present invention to provide an electronic returnless fuel system for a vehicle that reduces vapor generation and heat input in a fuel tank for the vehicle.
It is yet another object of the present invention to provide an electronic returnless fuel system for a vehicle with switchable jet pump operation for a saddle type fuel tank.
To achieve the foregoing objects, the present invention is an electronic returnless fuel system for a vehicle including a fuel pump to pump fuel from a fuel tank. The electronic returnless fuel system also includes a fuel rail fluidly connected to the fuel pump to distribute the fuel to an engine of the vehicle and a pressure transducer to sense pressure of the fuel from the fuel pump to the fuel rail. The electronic returnless fuel system includes a controller electrically connected to the pressure transducer and the fuel pump to control the pressure of the fuel from the fuel pump to the fuel rail at a set operating pressure. The electronic returnless fuel system further includes a pressure relief valve interconnecting the fuel pump and the fuel rail set a predetermined amount above the set operating pressure and at least one jet pump disposed in the fuel tank and fluidly connected to the pressure relief valve.
In addition, the present invention is a method of operating an electronic returnless fuel system for a vehicle. The method includes the steps of sensing a fuel level in a fuel tank of a vehicle and determining whether the sensed fuel level is less than a predetermined value. The method also includes the steps of raising an operating pressure of the fuel in the electronic returnless fuel system and determining whether the fuel level is increasing in the fuel tank. The method further includes the steps of returning to the operating pressure of the electronic returnless fuel system if the fuel level is not increasing.
One advantage of the present invention is that an electronic returnless fuel system is provided for a vehicle. Another advantage of the present invention is that the electronic returnless fuel system replaces the mechanical fuel pressure regulator with a pressure transducer and a pump speed controller to control fuel pressure by controlling a fuel pump of the fuel delivery module. Yet another advantage of the present invention is that the electronic returnless fuel system lowers fuel tank pressures. Still another advantage of the present invention is that the electronic returnless fuel system reduces vapor generation and heat input in a fuel tank for a vehicle. A further advantage of the present invention is that the electronic returnless fuel system has a switchable jet pump operation for a saddle type fuel tank.
Other objects, features, and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.